Search for the sgoldstino at √s from 189 to 202 GeV
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 494:3-4 (2000) 203-214
Abstract:
A search for the supersymmetric partner of the goldstino, the sgoldstino S, at LEP2 is presented. The production Sγ followed by S decay into two gluons or into two photons was studied at 189-202 GeV LEP centre-of-mass energies. No evidence for the S production was found and limits on the S mass corresponding to different theory parameters are given. (C) 2000 Elsevier Science B.V.Determination of the e+e- → γγ(γ) cross-section at centre-of-mass energies ranging from 189 GeV to 202 GeV
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 491:1-2 (2000) 67-80
Abstract:
A test of the QED process e+e- → γγ(γ) is reported. The data analysed were collected with the DELPHI detector in 1998 and 1999 at the highest energies achieved at LEP, reaching 202 GeV in the centre-of-mass. The total integrated luminosity amounts to 375.7 pb-1. The differential and total cross-sections for the process e+e- → γγ were measured, and found to be in agreement with the QED prediction. 95% confidence level (C.L.) lower limits on the QED cut-off parameters of Λ+ > 330 GeV and λ- > 320 GeV were derived. A 95% C.L. lower bound on the mass of an excited electron of 311 GeV/c2 (for λγ = 1) was obtained, s-channel virtual graviton exchange was searched for, resulting in 95% C.L. lower limits on the string mass scale, M(S): M(S) > 713 GeV/c2 (λ = 1) and M(S) > 691 GeV/c2 (γ = -1). (C) 2000 Published by Elsevier Science B.V.Measurement of J/psi and psi(2S) polarization in pp collisions at sqrt[s] = 1.8 TeV.
Phys Rev Lett 85:14 (2000) 2886-2891
Abstract:
We have measured the polarization of J/psi and psi(2S) mesons produced in pp collisions at sqrt[s] = 1.8 TeV, using data collected at the Collider Detector at Fermilab during 1992-1995. The polarization of promptly produced J/psi [psi(2S)] mesons is isolated from those produced in B-hadron decay, and measured over the kinematic range 4 [5.5]
Rapidity-rank structure of pp̄ pairs in hadronic Z0 decays
Physics Letters Section B Nuclear Elementary Particle and High Energy Physics 490:1-2 (2000) 61-70
Abstract:
The rapidity-rank structure of pp̄ pairs is used to analyze the mechanism of baryon production in hadronic Z0 decay. The relative occurrence of the rapidity-ordered configuration p M p̄, where M is a meson, and that of pp̄ adjacent pairs is compared. The data are found to be consistent with predictions from a mechanism producing adjacent-rank pp̄ pairs, without requiring 'string-ordered' p M p̄ configurations. An upper limit of 15% at 90% confidence is determined for the p M p̄ contribution. (C) 2000 Elsevier Science B.V.Inclusive ∑- and Λ(1520) production in hadronic Z decays
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 475:3-4 (2000) 429-447